2 * Copyright (c) 2012 Alex Hornung <alex@alexhornung.com>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
19 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
20 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
22 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
24 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
33 #include <sys/libkern.h>
34 #include <sys/module.h>
36 #include <sys/random.h>
37 #include <sys/sysctl.h>
39 #include <machine/specialreg.h>
41 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16))
42 #define RDRAND_SIZE 512
44 static int rdrand_debug;
45 SYSCTL_INT(_debug, OID_AUTO, rdrand, CTLFLAG_RW, &rdrand_debug, 0,
46 "Enable rdrand debugging");
49 struct callout sc_rng_co;
54 static void rdrand_rng_harvest(void *);
55 int rdrand_rng(uint8_t *out, long limit);
59 rdrand_identify(driver_t *drv, device_t parent)
62 /* NB: order 10 is so we get attached after h/w devices */
63 if (device_find_child(parent, "rdrand", -1) == NULL &&
64 BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0)
65 panic("rdrand: could not attach");
70 rdrand_probe(device_t dev)
73 if ((cpu_feature2 & CPUID2_RDRAND) == 0) {
74 device_printf(dev, "No RdRand support.\n");
78 device_set_desc(dev, "RdRand RNG");
84 rdrand_attach(device_t dev)
86 struct rdrand_softc *sc;
88 sc = device_get_softc(dev);
91 sc->sc_rng_ticks = hz / 10;
95 callout_init_mp(&sc->sc_rng_co);
96 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
97 rdrand_rng_harvest, sc);
104 rdrand_detach(device_t dev)
106 struct rdrand_softc *sc;
108 sc = device_get_softc(dev);
110 callout_stop_sync(&sc->sc_rng_co);
117 rdrand_rng_harvest(void *arg)
119 struct rdrand_softc *sc = arg;
120 uint8_t randomness[RDRAND_SIZE + 32];
121 uint8_t *arandomness; /* randomness aligned */
124 arandomness = RDRAND_ALIGN(randomness);
126 cnt = rdrand_rng(arandomness, RDRAND_SIZE);
127 if (cnt > 0 && cnt < sizeof(randomness)) {
128 add_buffer_randomness(arandomness, cnt);
131 kprintf("rdrand(%d): %02x %02x %02x %02x...\n",
140 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
141 rdrand_rng_harvest, sc);
145 static device_method_t rdrand_methods[] = {
146 DEVMETHOD(device_identify, rdrand_identify),
147 DEVMETHOD(device_probe, rdrand_probe),
148 DEVMETHOD(device_attach, rdrand_attach),
149 DEVMETHOD(device_detach, rdrand_detach),
155 static driver_t rdrand_driver = {
158 sizeof(struct rdrand_softc),
161 static devclass_t rdrand_devclass;
163 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL);
164 MODULE_VERSION(rdrand, 1);
165 MODULE_DEPEND(rdrand, crypto, 1, 1, 1);